Technical Field
The present disclosure relates to a power converter. More particularly, the present disclosure relates to a step up/down direct current (DC) converter.
Description of Related Art
As the technology develops, electronic products have become an indispensable means for people in their everydayness and business as well. In general, the electronic products are operated when providing with a suitable and normal electric power, thereby the electronic products may be suffered when the electric power applies abnormally.
Reference is made to FIG. 1, which is a circuit diagram of a conventional step up/down DC converter. The step up/down DC converter is connected between a power source Vin and the load RL and includes a power switch Q, an inductor L, a diode 2, and an output capacitor Co. The power switch Q is a MOSFET; the drain of the power switch Q is connected to the positive terminal of the power source Vin, the source thereof is connected to the cathode of the diode 2. The step up/down DC converter further includes a body diode connected to the drain and source of the power switch Q. One terminal of the inductor L is connected to the source of the power switch Q and the cathode of the diode 2, and the other terminal of the inductor L is connected to the negative terminal of the power source Vin. One terminal of the output capacitor Co is connected to the anode of the diode 2, and the other terminal of the output capacitor Co is connected to the negative terminal of the power source Vin. The load RL is electrically connected to the output capacitor Co in parallel. The level of the output electric power may be regulated to be higher than or lower than that of the input electric power by modulating the duty cycle of the power switch Q.
The conventional step up/down DC converter constituted by the power switch Q, the inductor L, the diode 2, and the output capacitor Co has advantages of effective cost and simple to make; however, it produces a higher ripple voltage on its output, this may cause errors in load.